I'm running Windows XP Home in a Dimension 4800.

The screen saver was OK until a few days ago. I had it set to bring up Mystify after 10 minutes. Mystify would stay up until any activity killed it.

Now it goes into an on-off cycle. Mystify stays up for about 1 minute, then returns to the previous active screen for 9 minutes. Total of 10 minutes. Then repeats indefinitely.

Changing the timing in Control Panel / Display / Screen Saver only changes the length of the cycle. Changing the selected screen saver doesn't fix it.

A thought: I'm not sure, but I think this may have started when I downloaded the SP2 upgrade.